/*
 *  textbox.c -- implements the text box
 *
 *  ORIGINAL AUTHOR: Savio Lam (lam836@cs.cuhk.hk)
 *  MODIFIED FOR LINUX KERNEL CONFIG BY: William Roadcap (roadcap@cfw.com)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "dialog.h"

static void back_lines(int n);
static void print_page(WINDOW *win, int height, int width);
static void print_line(WINDOW *win, int row, int width);
static char *get_line(void);
static void print_position(WINDOW *win);

static int hscroll;
static int begin_reached, end_reached, page_length;
static const char *buf;
static const char *page;

/*
 * refresh window content
 */
static void refresh_text_box(WINDOW *dialog, WINDOW *box, int boxh, int boxw, int cur_y, int cur_x) {
    print_page(box, boxh, boxw);
    print_position(dialog);
    wmove(dialog, cur_y, cur_x); /* Restore cursor position */
    wrefresh(dialog);
}

/*
 * Display text from a file in a dialog box.
 */
int dialog_textbox(const char *title, const char *tbuf, int initial_height, int initial_width) {
    int i, x, y, cur_x, cur_y, key = 0;
    int height, width, boxh, boxw;
    int passed_end;
    WINDOW *dialog, *box;

    begin_reached = 1;
    end_reached = 0;
    page_length = 0;
    hscroll = 0;
    buf = tbuf;
    page = buf; /* page is pointer to start of page to be displayed */

do_resize:
    getmaxyx(stdscr, height, width);
    if (height < 8 || width < 8) return -ERRDISPLAYTOOSMALL;
    if (initial_height != 0)
        height = initial_height;
    else if (height > 4)
        height -= 4;
    else
        height = 0;
    if (initial_width != 0)
        width = initial_width;
    else if (width > 5)
        width -= 5;
    else
        width = 0;

    /* center dialog box on screen */
    x = (COLS - width) / 2;
    y = (LINES - height) / 2;

    draw_shadow(stdscr, y, x, height, width);

    dialog = newwin(height, width, y, x);
    keypad(dialog, TRUE);

    /* Create window for box region, used for scrolling text */
    boxh = height - 4;
    boxw = width - 2;
    box = subwin(dialog, boxh, boxw, y + 1, x + 1);
    wattrset(box, dlg.dialog.atr);
    wbkgdset(box, dlg.dialog.atr & A_COLOR);

    keypad(box, TRUE);

    /* register the new window, along with its borders */
    draw_box(dialog, 0, 0, height, width, dlg.dialog.atr, dlg.border.atr);

    wattrset(dialog, dlg.border.atr);
    mvwaddch(dialog, height - 3, 0, ACS_LTEE);
    for (i = 0; i < width - 2; i++) waddch(dialog, ACS_HLINE);
    wattrset(dialog, dlg.dialog.atr);
    wbkgdset(dialog, dlg.dialog.atr & A_COLOR);
    waddch(dialog, ACS_RTEE);

    print_title(dialog, title, width);

    print_button(dialog, gettext(" Exit "), height - 2, width / 2 - 4, TRUE);
    wnoutrefresh(dialog);
    getyx(dialog, cur_y, cur_x); /* Save cursor position */

    /* Print first page of text */
    attr_clear(box, boxh, boxw, dlg.dialog.atr);
    refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);

    while ((key != KEY_ESC) && (key != '\n')) {
        key = wgetch(dialog);
        switch (key) {
            case 'E': /* Exit */
            case 'e':
            case 'X':
            case 'x':
                delwin(box);
                delwin(dialog);
                return 0;
            case 'g': /* First page */
            case KEY_HOME:
                if (!begin_reached) {
                    begin_reached = 1;
                    page = buf;
                    refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
                }
                break;
            case 'G': /* Last page */
            case KEY_END:

                end_reached = 1;
                /* point to last char in buf */
                page = buf + strlen(buf);
                back_lines(boxh);
                refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
                break;
            case 'K': /* Previous line */
            case 'k':
            case KEY_UP:
                if (!begin_reached) {
                    back_lines(page_length + 1);

                    /* We don't call print_page() here but use
                     * scrolling to ensure faster screen update.
                     * However, 'end_reached' and 'page_length'
                     * should still be updated, and 'page' should
                     * point to start of next page. This is done
                     * by calling get_line() in the following
                     * 'for' loop. */
                    scrollok(box, TRUE);
                    wscrl(box, -1); /* Scroll box region down one line */
                    scrollok(box, FALSE);
                    page_length = 0;
                    passed_end = 0;
                    for (i = 0; i < boxh; i++) {
                        if (!i) {
                            /* print first line of page */
                            print_line(box, 0, boxw);
                            wnoutrefresh(box);
                        } else
                            /* Called to update 'end_reached' and 'page' */
                            get_line();
                        if (!passed_end) page_length++;
                        if (end_reached && !passed_end) passed_end = 1;
                    }

                    print_position(dialog);
                    wmove(dialog, cur_y, cur_x); /* Restore cursor position */
                    wrefresh(dialog);
                }
                break;
            case 'B': /* Previous page */
            case 'b':
            case KEY_PPAGE:
                if (begin_reached) break;
                back_lines(page_length + boxh);
                refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
                break;
            case 'J': /* Next line */
            case 'j':
            case KEY_DOWN:
                if (!end_reached) {
                    begin_reached = 0;
                    scrollok(box, TRUE);
                    scroll(box); /* Scroll box region up one line */
                    scrollok(box, FALSE);
                    print_line(box, boxh - 1, boxw);
                    wnoutrefresh(box);
                    print_position(dialog);
                    wmove(dialog, cur_y, cur_x); /* Restore cursor position */
                    wrefresh(dialog);
                }
                break;
            case KEY_NPAGE: /* Next page */
            case ' ':
                if (end_reached) break;

                begin_reached = 0;
                refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
                break;
            case '0': /* Beginning of line */
            case 'H': /* Scroll left */
            case 'h':
            case KEY_LEFT:
                if (hscroll <= 0) break;

                if (key == '0')
                    hscroll = 0;
                else
                    hscroll--;
                /* Reprint current page to scroll horizontally */
                back_lines(page_length);
                refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
                break;
            case 'L': /* Scroll right */
            case 'l':
            case KEY_RIGHT:
                if (hscroll >= MAX_LEN) break;
                hscroll++;
                /* Reprint current page to scroll horizontally */
                back_lines(page_length);
                refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x);
                break;
            case KEY_ESC:
                key = on_key_esc(dialog);
                break;
            case KEY_RESIZE:
                back_lines(height);
                delwin(box);
                delwin(dialog);
                on_key_resize();
                goto do_resize;
        }
    }
    delwin(box);
    delwin(dialog);
    return key; /* ESC pressed */
}

/*
 * Go back 'n' lines in text. Called by dialog_textbox().
 * 'page' will be updated to point to the desired line in 'buf'.
 */
static void back_lines(int n) {
    int i;

    begin_reached = 0;
    /* Go back 'n' lines */
    for (i = 0; i < n; i++) {
        if (*page == '\0') {
            if (end_reached) {
                end_reached = 0;
                continue;
            }
        }
        if (page == buf) {
            begin_reached = 1;
            return;
        }
        page--;
        do {
            if (page == buf) {
                begin_reached = 1;
                return;
            }
            page--;
        } while (*page != '\n');
        page++;
    }
}

/*
 * Print a new page of text. Called by dialog_textbox().
 */
static void print_page(WINDOW *win, int height, int width) {
    int i, passed_end = 0;

    page_length = 0;
    for (i = 0; i < height; i++) {
        print_line(win, i, width);
        if (!passed_end) page_length++;
        if (end_reached && !passed_end) passed_end = 1;
    }
    wnoutrefresh(win);
}

/*
 * Print a new line of text. Called by dialog_textbox() and print_page().
 */
static void print_line(WINDOW *win, int row, int width) {
    int y, x;
    char *line;

    line = get_line();
    line += MIN(strlen(line), hscroll); /* Scroll horizontally */
    wmove(win, row, 0);                 /* move cursor to correct line */
    waddch(win, ' ');
    waddnstr(win, line, MIN(strlen(line), width - 2));

    getyx(win, y, x);
    /* Clear 'residue' of previous line */
#if OLD_NCURSES
    {
        int i;
        for (i = 0; i < width - x; i++) waddch(win, ' ');
    }
#else
    wclrtoeol(win);
#endif
}

/*
 * Return current line of text. Called by dialog_textbox() and print_line().
 * 'page' should point to start of current line before calling, and will be
 * updated to point to start of next line.
 */
static char *get_line(void) {
    int i = 0;
    static char line[MAX_LEN + 1];

    end_reached = 0;
    while (*page != '\n') {
        if (*page == '\0') {
            if (!end_reached) {
                end_reached = 1;
                break;
            }
        } else if (i < MAX_LEN)
            line[i++] = *(page++);
        else {
            /* Truncate lines longer than MAX_LEN characters */
            if (i == MAX_LEN) line[i++] = '\0';
            page++;
        }
    }
    if (i <= MAX_LEN) line[i] = '\0';
    if (!end_reached) page++; /* move pass '\n' */

    return line;
}

/*
 * Print current position
 */
static void print_position(WINDOW *win) {
    int percent;

    wattrset(win, dlg.position_indicator.atr);
    wbkgdset(win, dlg.position_indicator.atr & A_COLOR);
    percent = (page - buf) * 100 / strlen(buf);
    wmove(win, getmaxy(win) - 3, getmaxx(win) - 9);
    wprintw(win, "(%3d%%)", percent);
}
